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The ecu might just think the signal is currently out of its voltage range (if its hooked up right). I can display the speed the ECU is reading vs. the EA speedometer in real time with my OBDII reader. This should be 1/4 the speed the gauge reads, according to Gloyale's post.

I hooked the EJ Green/Red wire from the ECU to the Yellow/Red wire on the EA white gauge cluster plug. Is this right?

Any Chance you remember which white plug?

Was it at pin 4 of the round one at the back of the dash?

Or the 2 prong one that the dealer installed cruise control uses that's up above/behind fuse panel area?

IDK if you have factory or dealer cruise. Probably dealer since the FSM for 87 only has a cruise schematic for Digi-dash, MPFI cars (GL-10's).

I'm guessing that you need to tap the signal at the 2 prong connector up above the clutch pedal area/ behind fusebox.

Find the dealer cruise wiring by starting at the brake switch, and follow the loom that is smaller, seperate, and wrapped in a slightly different tape. It will junction with the VSS signal wire. trace it from there up to the 2 prong connector and tap your EJ wire there.

Or the 2 prong one that the dealer installed cruise control uses that's up above/behind fuse panel area?

IDK if you have factory or dealer cruise. Probably dealer since the FSM for 87 only has a cruise schematic for Digi-dash, MPFI cars (GL-10's).

I'm guessing that you need to tap the signal at the 2 prong connector up above the clutch pedal area/ behind fusebox.

Find the dealer cruise wiring by starting at the brake switch, and follow the loom that is smaller, seperate, and wrapped in a slightly different tape. It will junction with the VSS signal wire. trace it from there up to the 2 prong connector and tap your EJ wire there.

Nice description. I'll try tapping in elsewhere as you suggest. Then I'll make sure i'm getting a signal from the cluster, then I'll wire in the voltage divider so the ECU gets a happy voltage.

The white plug I'm talking about is the round one on the back of the cluster. I can't remember which wire I tapped into by count.

Ok, scratch all the vss conversation from before. I had the ECU hooked up to the correct wire all along. Read on:

Upon putting a meter on the reed switch signal at the cruise control computer connector (big one on the cuise box just above the hood latch lever) I found that it puts out 4.75v when closed and 0.3v when open (probably inductance). This should be within the acceptable range for the EJ ECU. I found that if the cruise computer was unplugged that I'd get a speed reading from the ECU. Plugged in, the ECU speed went to 0.0.

This led me to believe that the cruise computer was somehow interfering with the more sensitive ECU, perhaps drawing current from it or visa-versa. Fist I tried a diode to try and eliminate current flow in one direction or the other. No luck.

Then I tried a capacitor to isolate the ECU from the signal current but still letting it see the voltage changes. That was the ticket. It worked with both 100 micro-farad and 220 micro-farad capacitors. I just had these lying around, but probably any coupling cap will work. I soldered the 220 micro-farad in and shrink tubed it.

My cruise control and EJ ECU now both get a speed signal and work great.

Then I tried a capacitor to isolate the ECU from the signal current but still letting it see the voltage changes. That is the ticket. It worked with both 100 micro-farad and 220 micro-farad capacitors. I just had these lying around, but probably any coupling cap will work. I soldered the 220 micro-farad in and shrink tubed it.

My cruise control and EJ ECU now both get a speed signal and work great.

On the drive to work this morning the ECU was going haywire. Fans turning on individually, timing advance stuck at 45°, intermittent cut-outs, and died twice when coming to a stop, AND the ECU speed reading bounces all over from 0 to 200 mph...

I think the ECU VSS pin might be floating when the signal goes low from the reed switch. A pull-down resistor between the cap and the ECU should do the trick. Then I have to put a smaller cap in there so it doesn't keep the signal high for too long. Strange how it worked great last night and totally nuts this morning.

Upon a little more testing I found the following with cruise plugged in:

With the cruise off the vss signal pulses between .3v and 3v. With cruise on the signal pulses between 3v and 6v. This is enough to satisfy the ECU and it works great. When the cruise is off the ECU sees a signal below trigger voltage and reads 0 mph, causing all sorts of problems, as stated earlier.

Somehow the cruise is putting 3v dc on the vss wire. The plan:

Try putting a diode between the vss and cruise allowing the signal to move only to the cruise computer from the reed switch. Then, if the vss wire voltage remains consistent no matter what the state of the cruise, I'll boost the signal with a little switching transistor to 5v.

I got the VSS working as well as the cruise, FINALLY. I ended up putting a 5v regulator and a transistor network together to use the reed switch to control pulses to the ecu and ccu completely separately and isolated so they don't talk to each other. It works like a dream and the car drives perfectly. It pretty much takes the one pulsed signal and gives me two outputs that tie to ground every time the reed switch is open (inverted signal).

In the future, I will make a little micro controller which will convert the pulses to several so that I can match the ECU speed to the actual vehicle speed (tire size selector and pulse multiplier). A picaxe chip should be great for this since it's really easy code and completely reprogram-able.

Well, the swap has been running great for about 6 months, now. It made it through the winter and a few -10°F nights. Below around 10°F it would be VERY hard to start and almost kill the battery if it did start. Crank for a few sec, wait, crank, wait, crank, etc.. each time it might fire once or twice and then not continue to run. Above 10°F it would take about 1 crank to start.

The only codes are fuel vent solenoid (which doesn't exist), and fuel tank temp sensor (also doesn't exist). How the heck should I get rid of these? Weld a bung onto the tank for a sensor? Connect a vent solenoid? What have you guys done?

I found that the engine is hard to start on cold starts if it reads a wrong temperature in the tank, though once started runs perfectly. This was tested with a variety of resistors to simulate the sensor.

I am working thru a transplant of a EJ25 into my 74 VW Bus. Concerning your fuel temp /pressure codes, there is a company called Small Car performance in Wasington that specialized in VW-Suby swaps. They make a board that will fool 7 sensors including the fuel sensors in the EJ engines. The board has adjustable outputs. The product is 65 bones, but it would probably only cure annoying codes and not your cold start issues. When cold, the temp sensor tells the computer to adjust fuel/air mixture for extreme cold. Fooling the ECU prob won't help this situation. An actual temp sensor would prob be best bet if that is even feasible.

Wow, your project is lookin' great. I'm almost there, the fresh engine (2.2t) is hangin' in the stand ready to go into my 88 GL10T. The next hurdle is the wiring, don't know whether to tackle it myself or buy one from someone else. Whata' ya think? Do you ever get down Santa Fe way?, I'd love to see your rig. Keep up the good work, Steve.